WASHINGTON — The United States brutalized scores of terror suspects with interrogation tactics that turned secret CIA prisons into chambers of suffering and did nothing to make America safer after the 9/11 attacks, Senate investigators concluded Tuesday. The Senate Intelligence Committee's torture report, years in the making, accused the CIA of misleading its political masters about what it was doing with its "black site" captives and deceiving the nation about the effectiveness of its techniques. The report was the first public accounting of tactics employed after the Sept. 11, 2001, terrorist attacks, and it described far harsher actions than had been widely known.